Surface Modification Agent Research Articles

Surface modification of Si3N4 powder for hydrolysis control

The hydrolysis of Si3N4 powder was controlled by surface modification with Al(H2PO4)3 and Mg(H2PO4)2 with TEOS. The existence of Al(H2PO4)3 and Mg(H2PO4)2 catalyzed the hydrolysis of TEOS. From experimental results, the Si3N4 powder after surface modification exhibits a greatly-improved hydrolysis resistance than the initial Si3N4 powder in water at 60 and 120 °C. The surface modification had no clear influence on the dielectric loss of Si3N4 powders. By XPS analysis, the powders after surface modification showed the presence of P, Al, and Mg elements. It was proposed that the surface modification agent forms a strong bonding with the surface of Si3N4 particles.

Tannin-reinforced iron substituted hydroxyapatite nanorods functionalized collagen-based composite nanofibrous coating as a cell-instructive bone-implant interface scaffold

Bone defects account for a significant proportion of surgeries, increasing healthcare costs and complicating therapies. These factors necessitated cell-instructive bioengineering procedures to support and restore pre-existing bone function. Herein, iron-reinforced hydroxyapatite nanorod was used as an inorganic component, collagen/polycaprolactone was used as an organic component, and tannic acid was used as a surface modifier (onto nanorods), crosslinker, and functional agent. The inorganic–organic nanofibers were coated onto an implant surface using electrospinning. The nanocomposite nanostructural, contact angle, surface chemistries, thermomechanical, physicochemical, cytocompatibility, antioxidant potential, aspects of osseointegration ranging from cell adhesion, proliferation, differentiation, and bone remodeling at bone-implant zone in a rat model were studied. The results support that metal-phenolic networks on nanorods regulate interfacial interactions, nanorods cytocompatibility, antioxidant potential, and phase compatibility between organic and inorganic materials of scaffolds. The organic/inorganic nanocomposite better mimicked the bone matrix and better-supported MC3T3-E1 cell attachment, proliferation, matrix mineralization (intracellular alkaline phosphatase and calcium accumulation), and osteogenic gene expression (OPN, OCN, COL1A2, and RUNX2) to direct cell fate for bone reconstruction than its counterpart organic scaffold. The active bone formation and rebuilding of the bone-implant zone in rat models confirmed the bioactive potential of the studied nanocomposite, and it thus could be used as an interface scaffold to boost osteointegration.

Improving the stability of nanofluids via surface-modified titanium dioxide nanoparticles for wettability alteration of oil-wet carbonate reservoirs

The main challenge of the application of nanofluids for enhanced oil recovery (EOR) in oil-wet carbonate reservoirs is maintaining their stability under high-temperature and high-salinity which is normally seen in reservoir conditions. In this work, surface-modified TiO2 nanoparticles were synthesized by N-(2-Aminoethyl)−3-Aminopropyltrimethoxysilane (AEAPTMS) as a coupling agent for surface modification of nanoparticles. Zeta potential and dynamic light scattering analyses were used to evaluate the stability of the prepared nanofluids. Results indicated that nanofluids had high stability in 90 °C and 20 wt% salinity. The influence of nanofluids on wettability alteration of carbonate rocks was studied by measuring the contact angle value. Untreated rock samples were strongly oil-wet, with water advancing and receding contact angles of 165.1° and 166.2°, respectively. After treatment with 3wt% concentration of surface-modified TiO2 nanoparticles, the rock plate wettability changed to a water-wet state, with water advancing and receding contact angles of 37.6° and 48.2°, respectively. Suggested surface-modified TiO2 nanoparticles were more effective in wettability alteration of the rock surfaces compared to the un-modified TiO2 nanoparticles. Furthermore, higher concentration of nanoparticles, higher the ability of the nanoparticles on changing the rock wettability.

Enhanced photocatalytic nitrogen fixation of etched Ag-doped PM-CdS catalyst under visible light irradiation

Regarding the shortcomings of CdS as photocatalyst for photocatalytic N2 fixation, namely, inadequate visible-light response, fast recombination of the photogenerated charges, and poor adsorption of N2 on the surface, a trinity strategy made up of shape control, element doping and etching is proposed to enhance the photocatalytic performance. Etched Ag-doped PVP modified CdS (Ag/PM-CdS(e)) is fabricated for photocatalytic N2 fixation by problem oriented method. The morphology, chemical structure, optical and electronic properties of as-prepared photocatalysts are well characterized. The results show that PVP is an excellent surface modification agent, promoting the optical performance of CdS and avoiding particle agglomeration. The strong interaction between Ag and CdS enhances the separation and transfer of photogenerated electron-hole pairs. Importantly, etching induces a larger specific surface area, resulting in improved N2 adsorption on catalyst surface. Under the synergistic effect of trinity strategy, the visible light response performance of photocatalyst is greatly improved, and the transient photocurrent density of the Ag/PM-CdS(e) sample reaches 3.5 times that of pristine CdS. Unsurprisingly, Ag/PM-CdS(e) exhibits improved photocatalytic NH3 production (0.343 μg h−1 mg−1) under visible light irradiation by a factor of 4.97, 2.18 and 1.56 times compared with the pristine CdS, PM-CdS and Ag/PM-CdS, respectively. Meanwhile, Ag/PM-CdS(e) shows good stability in the process of NH3 production for four successive cycles, NH4+ production with a rate of 0.269 μg h−1 mg−1 can be observed after 960 min of reaction. Finally, an anticipated mechanism for the meaningful N2 photofixation enhancement is provided.

The N-terminal tail of the hydrophobin SC16 is not required for rodlet formation

Hydrophobins are small proteins that are secreted by fungi, accumulate at interfaces, modify surface hydrophobicity, and self-assemble into large amyloid-like structures. These unusual properties make hydrophobins an attractive target for commercial applications as green emulsifiers and surface modifying agents. Hydrophobins have diverse sequences and tertiary structures, and depending on the hydrophobin, different regions of their structure have been proposed to be required for self-assembly. To provide insight into the assembly process, we determined the first crystal structure of a class I hydrophobin, SC16. Based on the crystal structure, we identified a putative intermolecular contact that may be important for rodlet assembly and was formed in part by the N-terminal tail of SC16. Surprisingly, removal of the N-terminal tail did not influence the self-assembly kinetics of SC16 or the morphology of its rodlets. These results suggest that other regions of this hydrophobin class are required for rodlet formation and indicate that the N-terminal tail of SC16 is amenable to modification so that functionalized hydrophobin assemblies can be created.

Surface modification of the Ti surface with nanoscale bio-MOF-1 for improving biocompatibility and osteointegration in vitro and in vivo.

Biocompatibility and osteointegration of implants are highly desired in orthopedic and dentistry applications. The synthesis of a coating with ideal biocompatibility and osteogenic effect carries practical significance for improving the bio-inertness of pure Ti implants. Metal-organic frameworks (MOFs) are effective surface modification agents in bone regeneration applications. Bio-MOF-1, a classic type of biofriendly MOF with a bio-derived constitution, possesses biocompatibility and osteogenic potential resulting from its Zn core and adenine ligand. In this study, bio-MOF-1 coatings at multiple concentrations were synthesized on alkali-heat treated Ti, and their cytocompatibility and osteogenic properties were systematically examined both in vitro and in vivo. Coatings were characterized to confirm the successful synthesis of bio-MOF-1 coatings. These coatings exhibited advanced thermostability, excellent biocompatibility, and stable Zn2+ release, which up-regulated the expression of osteogenesis-related genes and proteins. Furthermore, bio-MOF-1 coating of Ti implants enhanced early osseointegration at the bone-implant interface. This study demonstrates the promising potential of bio-MOF-1 coatings with the osteogenic effect for surface modification in bone tissue engineering.

Capability of Organically Modified Montmorillonite Nanoclay as a Carrier for Imidacloprid Delivery

Organically modified clays have attracted increasing research attention for their various commercial and industrial applications, such as being carriers for pesticide delivery. Besides, the suitability and performance of commercially available organoclays could further promote their applicability. Hence, this study investigated the potential application of a commercially available alkylamine-modified montmorillonite (MMT) nanoclay as a carrier for a widely used insecticide, imidacloprid. X-ray diffraction and thermogravimetric analysis were employed to illustrate the arrangement, orientation, and conformation of surface-modifying agents (SMAs) on MMT nanoclay. It was observed that the clay was modified at an ∼1.0 cation exchange capacity, with the SMAs, especially octadecylamine, arranged in the MMT nanoclay as a bilayer to a pseudo-trilayer or a paraffin monolayer with a tilting angle of ∼25°, which indicated the nanoclay’s ability to adsorb a large amount of imidacloprid. The adsorption–desorption of imidacloprid to MMT nanoclay further confirmed this applicability. A high adsorption capacity (∼85 mg g–1) was observed, with a high reversibility in desorption, showing a hysteresis value of 0.75. Further, the adsorption kinetics and response of the nanoclay to imidacloprid revealed that, initially, a rapid sorption occurred due to a hydrophobic interaction. This was followed by a slower diffusion-controlled sorption due to hydrogen bonding to the internal binding sites. The releasing pattern of imidacloprid from the MMT nanoclay indicated its potential for the preparation of a slow-releasing pesticide formulation where the nanoclay will reduce the instantaneous release of the total amount of pesticide.

The toxicity analysis of PVP, PVA and PEG surface functionalized ZnO nanoparticles on embryonic as well as adultDanio rerio.

Globally, the production of zinc oxide nanoparticles (ZnO NPs) increased due to its wide applications including cosmetics, paints etc., and gets accumulated in the environment during their production, use or end-of-life. The toxic effects of the NPs vary with the presence of various surface modification agents. In the current report, toxic effect of bare and capped ZnO NPs with polymeric surface modifying agent including polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) is studied against adult as well as embryonic zebra fish. The surface capped NPs showed great variation in toxicity levels. It was observed that ZnO-PVA showed highly reduced toxic effects relative to ZnO-PEG and ZnO-PVP. Further, various environmental agents including humic acid can also have an impact on NPs toxicity. ZnO particles showed increased toxic effect in humic acid presence. The uptake of ZnO particles by D. rerio was high in the order of PVP-, PEG- and PVA- followed by bare-ZnO. The current investigation found that ZnO NPs dissolution and uptake are the major factors which cause the toxicity against adult as well as embryonic zebra fishes respectively.

De-sliming followed by froth flotation for the recovery of phosphorus and enrichment of rare earth elements from Florida waste clay

Reprocessing and valorization of secondary resources is a possible solution to alleviate the supply-demand disparity for critical materials. The current study investigated the recovery of P and enrichment of REEs from Florida waste clay (WC). Clays, dolomite, and quartz are the main associated gangue minerals, while apatite is the predominant P-bearing mineral, and monazite and xenotime are the rare earth minerals in this WC. A 1.5-in. diam. hydro-cyclone unit was initially employed for the removal of clays. Froth flotation was then examined for the separation of values from the cyclone underflow. Various depressants and surface modifying agents were assessed for both direct and reverse flotation separations. Results showed that the direct flotation does not offer a solution for the selective recovery of P from WC. Despite their documented affinity for apatite and rare earths, hydroxamic acid collectors do not produce a selective separation. A single-stage reverse cationic process provides a more economically viable route due to its capability to avoid the loss of REEs. Test results of the single-stage reverse cationic process indicated that the P2O5 grade was increased to 21 wt.% from an initial grade of ∼8 wt.% with a corresponding recovery of approximately 80%. The REE content was elevated from an initial value of 307.1 ppm to 800 ppm, with an 80% recovery resulting from the same process. The removal of clays, silicates, and carbonates up to a point to meet the medium-grade phosphate ore specifications also facilitates the subsequent recovery of REEs using chemical separation.

Sintesis dan Karakterisasi Silika Aerogel sebagai Adsorben Tumpahan Minyak

Silica aerogel made from basic sand beach has been synthesized with addition surface modifier agent trymethylchlorosilane (TMCS) as an absorben oil spill. This study has purposed for to analysize addition of TMCS to aerogel silica charateristic. Aerogel silica has been syntesized using sol-gel methode and ambient pressure drying methode (APD). Waterglass is synthesized by melting sea sand and NaOH solution. Waterglass is converted into a gel by adding acetic acid and ammonium hydroxide. Silica gel formed then dried and soaked in methanol to get alcogel. Alcogel then soaked with TMCS : Hexana : Methanol as long 24 hours at 50 oC , Subsequently soaked in a hexane solution and then dried to produce an aerogel The chracterization has been done are oil absorption capacity, porosity, functional group analysis, contact angel test, and silica aerogel morphology analysis. The highest oil absorption capacity is 5 time by it dry mass and highest porosty has been got is 31,5 %. Functional group analysis show the absorption pick on the wave number 789,86 cm-1 which shows the vibration-OSiCH3 and the wave number 549,72 cm-1 which shows the vibration –Si(CH3)3. From the contact angle test, the highest value was 92.5o, which indicated that the silica airgel was not yet hydrophobic. On morphology surface analysis using SEM has been got the size of particel 10,513 µm and 14,244 µm for volume ratio 1:1:1 and 2:1:1.

Sintesis dan Karakterisasi Silika Aerogel sebagai Adsorben Tumpahan Minyak

Silica aerogel made from basic sand beach has been synthesized with addition surface modifier agent trymethylchlorosilane (TMCS) as an absorben oil spill. This study has purposed for to analysize addition of TMCS to aerogel silica charateristic. Aerogel silica has been syntesized using sol-gel methode and ambient pressure drying methode (APD). Waterglass is synthesized by melting sea sand and NaOH solution. Waterglass is converted into a gel by adding acetic acid and ammonium hydroxide. Silica gel formed then dried and soaked in methanol to get alcogel. Alcogel then soaked with TMCS : Hexana : Methanol as long 24 hours at 50 o C , Subsequently soaked in a hexane solution and then dried to produce an aerogel The chracterization has been done are oil absorption capacity, porosity, functional group analysis, contact angel test, and silica aerogel morphology analysis. The highest oil absorption capacity is 5 time by it dry mass and highest porosty has been got is 31,5 %. Functional group analysis show the absorption pick on the wave number 789,86 cm -1 which shows the vibration-OSiCH 3 and the wave number 549,72 cm -1 which shows the vibration –Si(CH 3 ) 3 . From the contact angle test, the highest value was 92.5 o , which indicated that the silica airgel was not yet hydrophobic. On morphology surface analysis using SEM has been got the size of particel 10,513 µm and 14,244 µm for volume ratio 1:1:1 and 2:1:1.

Magnetic Nanoparticle-Containing Supports as Carriers of Immobilized Enzymes: Key Factors Influencing the Biocatalyst Performance.

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes.

Utilization of bamboo leaf silica as a superhydrophobic coating using trimethylchlorosilane as a surface modification agent

In recent years, there has been an increasing research interest regarding the development of superhydrophobic coating for various purposes with tetraethyl orthosilicate (TEOS) as the source of silica. Unfortunately, TEOS is hazardous as an alkoxide and need long step as well as time consuming to synthesize it. Typically, previous researches using fluoroalkylsilane (FOK) as the surface modification agent is containing fluoro compound which is not safety to use. This paper is aimed to develop a cost-effective and environmental-friendly superhydrophobic coating by utilizing bamboo leaf silica. This work was particularly conducted to develop the method of purification of bamboo leaf ash as the source of silica to produce superhydrophobic coating material. This method could be an effective and efficient way of preparing a superhydrophobic coating using silica bamboo leaf with eco-friendly solvent exchange agents. This observation used n-hexane, cyclohexane, isooctane as a solvent exchange, and trimethylchlorosilane (TMCS) as a surface modification agent which is not containing fluoro component. The initial bamboo leaf silica and purified silica were examined using XRD, BET, XRF, and SEM EDX Mapping to obtain essential information such as structure, porosity, purity, and surface topography. Also, the coated zinc plat with different solvents was assessed hydrophobicity by contact angle measurement and surface morphology by SEM. The efficient and effective formulation of the superhydrophobic coating was attained by applying n-hexane solvent, 13 %-v/v TMCS, 1.75 %-w/v of bamboo leaf silica was the highest of contact angle.

Intracellular Targeting of Poly Lactic-Co-Glycolic Acid Nanoparticles by Surface Functionalization with Peptides.

Nanoparticles (NPs) are a promising strategy for delivering drugs to specific sites because of their tunable size and surface chemistry variety. Among the availablematerials, NPs prepared with biopolymers are of particular interest because of their biocompatibility and controlled release of encapsulated drugs. Poly lactic-co-glycolic acid (PLGA) is one of the most widely used biopolymers in biomedical applications. In addition to material choice modulation of the interaction between NPs and biological systems is essential for the safety and effective use of NPs. Therefore, this work focused on evaluating different surface functionalization strategies to promote cancer cell uptake and intracellular targeting of PLGA NPs. Herein, cell-penetrating peptides (CPPs) were shown to successfully drive PLGA NPs to the mitochondria and nuclei. Furthermore, the functionalization of PLGA NPs with peptide AC-1001 H3 (GQYGNLWFAY) was proven to be useful for targeting actin filaments. The PLGA NPs cell internalization mechanism by B16F10-Nex2 cells was identified as caveolae-mediated endocytosis, which could be inhibited by the presence of methyl-β-cyclodextrin. Notably, when peptide C (CVNHPAFAC) was used to functionalize PLGA NPs, none of the tested inhibitors could avoid cell internalization of PLGA NPs. Therefore, we suggest this peptide as a promising surface modification agent for enhancing drug delivery to cancer cells. Finally, PLGA NPs showed slow release kinetics and low cytotoxic profile, which, combined with the surface functionalization strategies addressed in this study, highlight the potential of PLGA NPs as a drug delivery platform for improving cancer therapy.

Thymine as a Biocompatible Surface Passivator for a Highly Efficient and Stable Planar Perovskite Solar Cell

The inevitable defects on the surface of the perovskite layer seriously reduce the efficiency and stability of perovskite solar cells. In this work, thymine, one of the four nucleobases in DNA, is developed as a multifunctional modification agent to passivate the uncoordinated Pb2+ on the perovskite film surface via post-treatment. Spectral data confirm that the surface defects of the perovskite film are effectively passivated via a strong interaction between the Pb ion and carbonyl group. Photoluminescence spectral and electrochemical impedance spectral results demonstrate that the defect-induced recombination of charge carriers at the interface is suppressed. The thymine-modified planar perovskite solar cells exhibit better charge collection, and the fill factor and power conversion efficiency are increased. Moreover, the hydrophobic nature of thymine also significantly improves the humidity stability of the solar cells. The unencapsulated passivated solar cells maintain 68% of the initial efficiency after 1000 h of exposure in the air with a relative humidity of 50 ± 5%. This work provides an effective and eco-friendly surface modification agent for improving the performance of perovskite solar cells.

Reduced graphene oxide/cellulose microfiber hybrid from the Vietnamese Nipa palm tree: Synthesis, properties, and applications for preparation of poly(methyl methacrylate) composite

Cellulose microfibers were successfully fabricated from Vietnamese Nipa palm by mechanical and chemical treatments. The Nipa palm petioles were simply rolled, pressed, and separated. They were then pretreated with an alkaline solution and submitted to acid hydrolysis to remove the impurities (tCell). The microfibers were reinforced with reduced graphene oxide to form a hybrid that was reduced with hydrazine hydrate in the last stage (tCell-rGO). The structure and properties of tCell and tCell-rGO were evaluated by FTIR, XRD, DSC, TGA, SEM, BET, and the sheet resistance. It was observed that the treated cellulose microfibers exhibited a diameter of 10–20 μm and had good crystallinity in the structure. Both tCell and tCell-rGO exhibited low-density values of 1.52 kg/m3 and 0.58 kg/m3, respectively, and had good specific surface area values of 11.2 m2/g and 13.0 m2/g, respectively. These results supported the decrease in the density and the increase in the specific surface area of the tCell-rGO samples in comparison with the tCell. The existence of rGO sheets in the cellulose microfiber matrix resulted in changes in the structure, arrangement, and crystallization of pristine microfibers. The thermal property and electrical conductivity of the reinforced GO cellulose microfibers were significantly improved. rGO not only showed its role as a surface modification agent that helps the cellulose microfibers disperse better in the non-polar substrate, but also contributed to the increase of the heat-stable and mechanical properties of polymer. The thermal stability of tCell-rGO/PMMA composite was notably improved more than 40°C in maximum decomposition temperature by an emulsion polymerization technique. The material based on cellulose microfibers from the Vietnamese Nipa palm tree and reduced graphene oxide overcame some disadvantages such as the poor heat resistance, poor dispersion of the original fibers in the non-polar polymer and displayed great potential for environmentally friendly future applications.

HYDRAULIC FRACTURING DESIGN IMPROVEMENTS BY PROPPANT FLOWBACK MITIGATION METHOD APPLICATION DURING HYDROCARBON PRODUCTION

Proppant flowback after hydraulic fracturing treatment is quite a serious challenge that causes damage to both downhole and surface equipment, leading to unwanted workovers and production suspension, or other negative outcomes. Some special methods including preventive as well as corrective measures already exist in the industry to overcome the proppant flowback problems. However, there is no clear guidance on how to choose the method for certain conditions, particularly during the hydraulic fracturing design stages. Therefore, the authors conducted a comprehensive review of fourteen preventive technologies to systematize them and to propose an initial decision-making approach. The following methods were considered in this paper: Resin Coated Proppants (RCP), RCP with Activator, RCP with Nanoparticles, Proppant with Liquid Resin Systems (LRS), Proppant with Surface Modification Agents (SMA), Proppant with Proppant Consolidation Aid (PCA), Cylindrical Proppant, Microfibers, Thermoset Resin Fibers, Thermoset Film Strips, Deformable Isometric Particles (DIP), Expandable Proppants, Polymer Surface Modified Proppants, and In-situ Formulated Proppants. The review reveals physical, chemical, and technological properties of each method to select criteria for effective screening. So, the reader could find the appropriate proppant flowback mitigation method corresponding to a particular reservoir and the well conditions during the initial hydraulic fracturing design stages.

Silver-Based Nanomaterials as Therapeutic Agents Against Coronaviruses: A Review.

Since the identification of the first human coronavirus in the 1960s, a total of six coronaviruses that are known to affect humans have been identified: 229E, OC43, severe acute respiratory syndrome coronavirus (SARS-CoV), NL63, HKU1, and Middle East respiratory syndrome coronavirus (MERS-CoV). Presently, the human world is affected by a novel version of the coronavirus family known as SARS-CoV-2, which has an extremely high contagion rate. Although the infection fatality rate (IFR) of this rapidly spreading virus is not high (ranging from 0.00% to 1.54% across 51 different locations), the increasing number of infections and deaths has created a worldwide pandemic situation. To provide therapy to severely infected patients, instant therapeutic support is urgently needed and the repurposing of already approved drugs is presently in progress. In this regard, the development of nanoparticles as effective transporters for therapeutic drugs or as alternative medicines is highly encouraged and currently needed. The size range of the viruses is within 60–140 nm, which is slightly larger than the diameters of nanoparticles, making nanomaterials efficacious tools with antiviral properties. Silver-based nanomaterials (AgNMs) demonstrate antimicrobial and disinfectant effects mostly by generating reactive oxygen species (ROS) and are presently considered as a versatile tool for the treatment of COVID-19 patients. Other metal-based nanoparticles have been primarily reported as delivery agents or surface modifying agents, vaccine adjuvant against coronavirus. The present review summarizes and discusses the possible effectiveness of various surface-modified AgNMs against animal coronaviruses and presents a concept for AgNM-based therapeutic treatment of SARS-CoV-2 in the near future.

Acid etching and silica coating effects on Y-TZP topography and ceramic/resin cement bond strength

Zirconia-based (Y-TZP) dental prostheses' retention loss remains one of the most frequently reported difficulties in dental practice. Selective Infiltration Etching (SIE) treatment has been proposed to alter the final Y-TZP topography improving its bond strength to resin cement. SIE consists of glass film deposition on the Y-TZP surface before glass removal with 10% hydrofluoric acid etching. This study's objective was to investigate the effects of SIE protocol steps on Y-TZP topography and its consequence on its bond strength to resin cement. The SIE protocol was divided into two main steps: silica coating (first step) and glass dissolution by hydrofluoric acid (second step), and the null hypothesis was that the SIE treatment has the same bond quality independently of the HF exposition time. Atomic Force Microscopy (AFM), Scanning Electron and Transmission Electron microscopy were used to characterize the zirconia surfaces. The bond strength was evaluated by the interfacial fracture toughness test, and data were analyzed by ANOVA and Tukey's Test (5%). As the main result, it was shown that, when exposed during sufficient time, the 10% HF can etch zirconia at room temperature, which is responsible for topographic changes, significantly improving the bond quality. Additionally, no glass components or dihedral angles modifications were observed at Y-TZP grain boundaries after silica coating. With the study limitations, it was possible to infer that the surface-modifying agent in SIE protocol is the HF etching, and the null hypothesis was rejected.

Fabrication of superhydrophobic polyethersulfone-ZnO rods composite membrane

The development of superhydrophobic membrane has gained more attention. The current methods for superhydrophobic surface mostly involve fluorosilanes as surface modification agent which is expensive and harmful to the environment. We herein report, simple and cost effective, fabrication of novel superhydrophobic polyethersulfone-composite membranes. The superhydrophobicity of the membrane surface was achieved by growing ZnO rods ex-situ followed by modification with stearic acid. SEM results showed the presence of ZnO rods with the length ranging from 1 µm to 11 µm on the membrane surface while AFM results revealed high surface roughness. The as-prepared membrane exhibited high water repellent with contact angle of ~163° and excellent superoleophilicity. The PES-ZnO rod-SA modified membrane could be an excellent candidate for oil-water separation.